Abstract: Consciousness, in particular phenomenal, qualitative
experiences like pain, is not the sort of thing that can be seen, measured,
weighed or otherwise observed from an external perspective. Consciousness
is arguably a categorically private phenomenon, non-identical to its publicly
observable correlates. I develop the idea that consciousness and its correlates
inhabit two mutually non-interacting explanatory spaces, 1st person and
3rd person, respectively. Since well-formulated 3rd person explanations of
behavior are restricted to public observables such as brains, bodies and
environments, private experiences such as pain are barred from playing a role in
such explanations. This constitutes a clean solution to the problem of mental
causation: consciousness and its physical correlates don't causally interact since they are in different explanatory
spaces. This means that consciousness isn't epiphenomenal with respect to
observable behavior: a phenomenon can only be fairly described as epiphenomenal (causally inert or
inefficacious) with respect to another if they inhabit the same explanatory
space.

It’s perhaps
an underappreciated fact about consciousness that no conscious experience has
ever been observed. No one has ever seen a pain, a sensation of red, a feeling
of elation, or any other instance of a phenomenal feel. What we can observe are
the physical and behavioral correlates of such things, but experiences
themselves are undergone or had, not observed. We don’t even observe our own
experiences. Instead, as conscious subjects we consist of them as they
succeed each other in consciousness. We might have the feeling (yet another
experience) that we are in an observational relationship to our experience, but
this an illusion. There is no observing self sitting behind experience that
witnesses it.[1]

What we
witness or observe is the world outside the head, and experience is the medium
in and by which the world is presented. The world appears in experience,
where part of that experience is the sense of being a self to whom the world
appears. As Thomas Metzinger,
Antti Revonsuo and some other representationalist
philosophers suggest, the whole ensemble of experience, of a stable me looking
out at a more or less coherent world, can be construed as a qualitatively
expressed reality model,
a virtual reality that normally corresponds at least to some extent with what’s outside
the head. Each conscious being is possessed of such a model, and it constitutes
for each of them a private subjective reality, in contrast with the intersubjective
reality modeled by science and other empirical pursuits. Subjective realities
are not visible from an external, 3rd person perspective, only their physical
correlates in the brain and body are visible. Consciousness itself is a
categorically private affair, which generates the problem of other minds: you
can't observe another creature's consciousness, you can only draw inferences
concerning it from its behavior and internal structure.

I will argue
that the privacy of phenomenal consciousness (e.g., experienced pain, red) makes it impossible for it to play a role in 3rd
person explanations of behavior. Consciousness doesn’t appear intersubjectively,
and it’s only intersubjectively observable entities and processes that can play
ascertainable roles in scientific accounts of phenomena. This means that
as far as science is concerned, consciousness isn’t even epiphenomenal. The whistle of Huxley’s steam engine exists along side the engine,
but is causally inert with respect to its operations, hence is causally epiphenomenal.
Since consciousness isn’t a publicly observable object or event it doesn’t
exist intersubjectively; it doesn’t exist along side the brain and behavior,
which are public objects and events. So qualitative conscious states don’t have the
opportunity of playing, or not playing, a causal role with respect to the brain
and behavior. Another way of putting this developed below is that consciousness doesn’t
inhabit the same explanatory space as do the physical objects of
scientific theories, including theories of human behavior which have at their
disposal all the entities and processes intersubjectively described by biology
and neuroscience.

This view
does not entail that mental states such as beliefs and desires can’t play roles in 3rd person
accounts of behavior. Psychological explanations that invoke intentional states
need not assume that the private phenomenal aspect
of such states (when conscious) is causally effective.[2]
We can ascribe beliefs and desires to agents and rightly think that as
functional, information bearing states, with all the causal powers of their physical realizers, they
participate in explaining behavior. But we need not suppose that the
unobservable subjective experience of having such states (when conscious) adds anything to what
the observable neural instantiations and physical manifestations of such states
accomplish in controlling and constituting action.

The
privacy constraint on consciousness

It might seem
that in claiming the categorical privacy of consciousness, what I will call the
privacy constraint on consciousness, I’m begging the question about what
consciousness might be. After all, if conscious states turn out to be identical
to some variety of physical states, for instance a certain collection of active
neural processes, then wouldn’t it be the case we can observe conscious
states just by observing those processes? Or if they turn out to be identical to
physically realized functions, for instance neurally instantiated
representational, information-carrying functions, wouldn’t we then actually
see consciousness were we to observe the system carrying out those
functions? The reply, it seems to me, is fairly straightforward. No: on those
accounts what you’re observing isn’t conscious experience itself but its
publicly observable sufficient conditions. If you were to observe in their
entirety what turn out to be the sufficient conditions of my being in
excruciating pain, that wouldn’t be to see the pain itself, since
pain itself is only something that is had by the system (me, the human organism)
that instantiates those conditions. My pain is an experienced element of a
conscious reality model that appears for me alone, that exists for me
alone as a particular locus of consciousness. Like other phenomenal feels, it is
a categorically 1st person reality. It is simply not in the cards for pains or
other conscious experiences to become 3rd person objects of public observation
in the way that (what might turn out to be) their sufficient physical or
functional conditions are public objects. No matter how hard you look at the
sufficient conditions of consciousness, you won’t see consciousness itself. It
is this fact, along with the qualitative nature of conscious states, that makes
explaining consciousness so difficult. How does something categorically private
and 1st personal come to exist as a result of conditions in the 3rd
person world constituted by public objects? This, of course, is one way of
stating the so-called “hard problem” of consciousness.

Although it
may not beg the question about what explains consciousness, the
privacy constraint does seem to rule out certain answers to the
hard problem. If consciousness really can’t be observed from the outside, but
only had “on the inside,” then it isn’t likely that it will be a causal
effect or product of what the brain and body are doing. Public
objects generally produce effects that are themselves publicly visible.
Observable neural states and systems, for instance those that precisely
correlate with my excruciating pain, have many observable effects, including my
grimacing, moaning, verbal reports of pain and the like. Were pain itself a
further causal effect or product of such processes, we’d expect to see it sitting there
in public space, but of course we don’t. As Daniel Dennett points out, there is
no “second transduction” that takes us from neural states to non-physical mental
states, or at least no evidence of such a thing; there is no phenomenal “juice”
or “milk” that the neural correlates of consciousness secrete which could itself
become a public object.[3]
Light waves, sound waves, chemical odorants, pressure and heat on my skin, and
other physical inputs to my sensory system all get transduced into neural
activity, but neural activity doesn’t generate a further effect beyond
more neural events and, sometimes, overt behavior. If a heretofore undetected
effect someday comes to light, for instance a holographic aura that shows up on
a yet to be devised consciousness detector, that still won’t be
consciousness, such that my experience of pain suddenly enters the public
domain. My pain is, and will always be, only present to me; it only exists
for me. The same goes for all my experience.

This suggests
that consciousness, a categorically private affair, might be some sort of
non-causal entailment of whatever its publicly observable sufficient
conditions turn out to be. I won’t pursue here what I think might be a fruitful
line of inquiry into the hard problem: that, as Metzinger and other
representationalist philosophers suggest, our being certain sorts of
representational systems entails our being conscious systems, where that
entailment is a matter of instantiation, not causation.[4]
I only want to say that the privacy constraint on consciousness isn’t going
away, and that it prevents us from claiming a literal and complete identity
between public states of affairs on the one hand and consciousness on the other.
If consciousness really is private, and we are realists, not eliminativists,
about its existence,[5]
then it can’t literally be the same thing as its publicly observable
sufficient conditions, whatever those turn out to be.

First
person explanatory space

Conscious,
qualitative experiences participate in what I’ll call 1st person
explanatory space, such that for instance when explaining why I wince, I
might very well tell you I’m in pain. As we’ve seen, my pain is a 1st
person state or event available only to me, and I experience it as playing a
causal role in my behavior. It very much seems to me that my wincing is caused
by my pain: were it not for the pain I wouldn’t be wincing. Other conscious
subjects will likewise attest to the causal efficacy of their phenomenal states.
Martha testifies that if she didn’t have the conscious experience of tasting
crème brulee, she wouldn’t be eager to order it at every opportunity. Mike says
that the conscious experience of terminal boredom keeps him away from staff
meetings, and so forth. All such explanations invoke private, 1st
person, subjective phenomenal feels as causally active in generating behavior.
Moreover, for conscious subjects the reality of such experiences can’t be placed
in doubt. Although the veridicality of an experience as a faithful
representation of the world outside the head can be doubted (is this a dagger I
see before me?) the sheer existence of the experience cannot. Nor can we as
subjects transcend experience. There is no non-experiential perspective
we can escape to from which to inspect experience. As Metzinger puts it, as
conscious beings we live entirely inside our “ego tunnels.”[6]
So the phenomenal experiences of 1st person explanatory space
participate in an indubitable and untranscendable individual private
subjective reality that exists for each conscious subject.

Although they
are not available to public observation, conscious states are routinely
recruited in 3rd person, intersubjective explanations of
behavior; they are ascribed causal roles in conjunction with, but distinct from,
publicly observable brains, bodies and environments. We generally tend to
believe that Martha, Mike and the rest of us do what we do as a result of the
phenomenal aspect of conscious states, where that aspect has causal power over
and above what the brain is doing. Discussing the role of conscious qualitative
states (qualia) in explaining behavior, Avshalom Elitzur suggests that “Alice’s
kiss may take a bit longer thanks to the additional effect of love’s
quale, and the qualia of hunger and fear may add some speed to the
rabbit’s and the fox’s race” (original emphasis).[7]
And writing for the National Academy of Sciences, biologist Anthony Cashmore
says “I suggest that … consciousness heightens our desire to listen to music,
for example, or to watch or participate in sporting activities.”[8]
The general idea is clear enough: the qualitative aspect of conscious states
adds an extra causal “push” beyond what their neural correlates contribute.
Although I haven’t explored the empirical research on folk beliefs about mental
causation, I suspect that something like this idea might be widespread.

But of course
the claim that phenomenal consciousness has its own proprietary causal role
generates the problem of mental causation, or more specifically, the problem of
phenomenal causation: how do private phenomenal feels like pain, taken as
non-identical to their public neural correlates, help to cause the physical
events we call behavior? What is their special causal contribution to behavior
over and above what the physical brain and body accomplish? Although most of us
are realists about the existence of conscious states and although we generally
suppose they are causally efficacious, integrating them into 3rd
person explanations of behavior is notoriously problematic. No viable accounts
of phenomenal-physical interaction or influence have been forthcoming, despite
centuries of speculation on this problem.[9]
Of course, if, contrary to the privacy constraint on consciousness, phenomenal
feels turn out to be identicalto some set of physical processes,
then consciousness doesn’t have a special causal contribution to make since its
causal powers are exactly those of the physical processes it’s identical to.
This neatly solves the problem of mental causation, but as explained above, I
think it's difficult to sustain the claim that consciousness is identical to its
physical correlates.

Third
person explanatory space

The
difficulty of integrating phenomenal feels, taken as non-identical to
physical processes, into 3rd person explanations of phenomena results
from the fact that such explanations deal only in public observables: what can
be seen, measured and confirmed to exist by any suitably placed observer, using
whatever equipment might be necessary to carry out the observation. Observables
are thus the basic elements of 3rd person explanatory space, and they
constitute public intersubjective reality: what we all generally agree
exists independently of the private subjective reality of each person’s
conscious experience. Observables having to do with human persons – their
brains, bodies, and physical and social environments – are uncontroversially
real elements of the 3rd person explanatory space having to do with
human behavior.

Of course we
observe and routinely take into account publicly available reports of
conscious experiences when constructing explanations of behavior. But
experiences themselves aren’t in 3rd person explanatory space since
they aren’t intersubjectively available. They cannot be seen, measured, weighed
or otherwise captured from an outside perspective. As a result, their causal
connection to or influence on what is observable, namely bodies and their
constituents, is irredeemably obscure (hence the puzzle of phenomenal causation
as explained above). But for each experiential report adduced in explaining
behavior, we can in principle observe the accompanying physical states
and processes, and it is these, not experiences, that can play
well-substantiated, unequivocal roles in 3rd person accounts of
behavior. Indeed, without them there would be no behavior to account for.

In explaining
my pain behavior – wincing, moaning, reports of pain, learning to avoid exposed
live electrical wiring, etc. – we can in principle trace the course of physical
events that occur between my contact with an object (the live wiring, let us
suppose) and all subsequent neurally realized internal states and overt
behaviors. There are successive neural and/or behavioral events for each stage
of the process, however we carve it up in terms of ordinary language
attributions of mental states, including beliefs, desires and phenomenal
experiences. In explaining and predicting my behavior, you will of course
attribute to me a desire to avoid painful episodes and a newly acquired belief
that contact with live wires causes pain. You will also assume, correctly, that
I undergo experiences of pain. But a properly intersubjective, as opposed to
subjective, explanation need not and cannot suppose there are unobservables
which ground or back up these attributions, on pain (so to speak) of trafficking
in explanatory posits which lack any public evidentiary basis.

Beliefs,
desires and other intentional and motivational states – a subset of mental
states – are perfectly real, observable attributes of the behaving system. After
all, we attribute beliefs and desires on the basis of physical,
functional and behavioral criteria constituted by 3rd person
observables: how I act in the presence of exposed wiring; my reports of
intentional states related to avoiding contact with them; the neural circuitry
subserving my harm-avoidance and damage-minimizing functions, including C-fibers
and other specialized neural networks; and my brain systems subserving memory,
motivation, deliberation, speech and action. Most important for the present
argument, the causal efficacy of intentional mental states in explaining
behavior need not appeal to anything over and above the causal powers of their
observable physical realizers, whatever those turn out to be. So 3rd
person explanations of behavior can uncontroversially include this subset of
mental states as physically and functionally real, as causally effective
elements within intersubjective explanatory space.

Barring
phenomenal feels from 3rd person explanations

What 3rd
person explanations cannot appeal to, however, is the causal power of the
conscious phenomenal aspect of mental states construed as something
non-identical to their physical realizers. This is because that phenomenal
aspect, unlike the physical realizers, isn’t observable – it only exists for
particular subjectivities, so is a denizen of 1st person, not 3rd
person, explanatory space. Matters would be different if we could claim a
literal identity between the publicly observable conditions sufficient for
phenomenal consciousness and consciousness itself, since in that case
consciousness would have exactly the same causal powers as its observable
realizers. But as seen above we can’t claim such an identity: the privacy
constraint on consciousness rules that out. So although we commonly appeal to
phenomenal feels like pain when explaining behavior from a 3rd person
perspective, I suggest we are making an unwarranted causal claim in doing so. We
can’t see, observe, measure or otherwise directly ascertain the existence of
phenomenal feels from an external vantage point, only their physical and
behavioral correlates. Those correlates do all the causal work in properly
formulated 3rd person explanations, and such explanations can
appeal to functionally efficacious intentional (mental) states as realized by some of those
correlates. But an appeal to phenomenal experience as a causal factor in behavior
violates the primary epistemic constraint on intersubjective accounts of
phenomena: that the elements participating in such accounts be publicly
observable, that they provably exist in 3rd person explanatory space.
To allow unobservable experiences to play explanatory roles in 3rd
person explanations is no more justifiable than allowing ghosts, spirits, souls
or other empirically unevidenced entities to play such roles: all unobservables
are properly ruled out as explanatory non-starters.

But of course
the response comes: we have good evidence that phenomenal feels exist and that
they play causal roles, namely that we undergo unequivocally real conscious
experiences of pains, pleasures, tastes, sights, sounds – the whole rich ensemble of our
qualitative lives – and we experience these phenomenal states as causally
central to our lives. Doesn’t that count as good evidence that conscious
experience, as distinct from the neural states that correlate with it, plays a role
in 3rd person explanations of behavior? No, it does not. I am not
denying the reality of conscious experience for the experiencing subject,
including the experience that such states are causally effective. Consciousness
is undeniably real and exists in nature, since subjects exist in nature. But
however vivid the experience of phenomenal causation might be, it doesn’t prove
that qualitative experiences such as consciously felt sensations and emotions are
in fact working along side physical systems in generating behavior, which is
what 3rd person explanations would require. To prove that, we’d have to
observe experience operating as an additional causal factor over and above the
brain, body and environment, which is exactly what can’t be done since
experiences are intersubjectively invisible. Phenomenal consciousness doesn’t exist in 3rd
person explanatory space, in reality as modeled by intersubjective, empirical
disciplines, so is necessarily barred from playing a role in 3rd
person explanations of behavior.

As persons,
we are both conscious subjects and observable physical entities, so we are
simultaneously situated in both subjective and intersubjective realities. As a
result, we are well acquainted with the elements that participate in their
respective explanatory spaces, 1st and 3rd person: private phenomenal
experiences on the one hand and public observables such as physical objects on
the other. We are, therefore, naturally inclined to combine elements from both
explanatory spaces in our 3rd person accounts of behavior. But good explanatory
practice requires we resist this temptation, since 3rd person accounts can’t
traffic in unobservables. Resisting it, I suggest, effectively solves (or
dissolves) the problem of mental causation, at least construed as the problem of
how phenomenal feels could possibly influence physically instantiated behavior
control mechanisms. The answer is straightforward: they don’t, and we should
stop trying to concoct metaphysically extravagant, conceptually convoluted, or
empirically unwarranted accounts by which they do.

In his
PNASpaper,
Anthony Cashmore insists that "...there must be a mechanism by which
consciousness does influence behavior. There must be a flow of information from
consciousness to neural activity" (p. 4). But according to my analysis, the
best hypothesis is that there is no such mechanism. There is no causal
interaction between consciousness and neural activity since they inhabit
different explanatory spaces, those connected with subjective and
intersubjective reality respectively. These spaces aren’t the sort of things that
could exert either mutual or one-way causal influence on one another. Cashmore
also asks what seems to be a straightforward question: “…what is the
evolutionary selective advantage of consciousness?” But from a 3rd
person perspective it isn’t consciousness that was naturally selected
for, but the neurally instantiated higher-level behavior control systems that
we’ve recently found to be associated with consciousness.[10]
Again, in rigorous scientific practice we have to segregate the unobservables
from the observables in intersubjective accounts of the world, both as things to
be explained and as things that do explanatory work.

Phenomenal
feels as convenient explanatory fictions

Of course,
declaring such a policy isn’t likely to change our everyday non-rigorous
practice of citing qualitative conscious states in 3rd person
explanations of behavior, nor should it.[11]
So long as we don’t imagine there’s an accepted evidence-based account of
phenomenal-physical causation that backs up such claims (there is no such
account), no great harm arises: phenomenal feels will continue to serve as very
convenient 3rd person explanatory fictions even when the physicalist
and functionalist story behind behavior gets completely filled in. After all,
their co-variance with behavior and brains states is very reliable, so their
predictive power remains what it was. Since there will always be accompanying
physical correlates that from an intersubjective standpoint reliably get the
behavioral job done, discovering the intersubjective truth about phenomenal
causation, namely that there is none, does not disempower or diminish us. We
remain just as rational, smart, empathetic, sensitive and emotionally and
interpersonally skilled (or unskilled) as we were before. It’s just that,
strictly speaking (as we try to do in philosophy and science)
the 1st and 3rd person explanations of these virtues don’t
causally interact.

Although
explanations of action that give qualitative experience a causal role are
misplaced from a 3rd person perspective, they pay important tribute
to the undeniable 1st person subjective reality of having
phenomenal feels and experiencing them as causally effective. The experience of
phenomenal causation is not going to go away, whatever our intersubjective, 3rd
person theory says about the causal role of consciousness. Moreover, conscious
states won’t ever stop mattering to us as individual subjects, so we have
no choice but to take phenomenology seriously in human affairs and the affairs
of other sentient systems. For instance, we must continue to obey the ethical
injunction to minimize unnecessary conscious suffering when considering the
effects of individual actions and public policy.

Consciousness isn’t epiphenomenal

A perhaps
surprising and paradoxical entailment of this view is that consciousnesscan’t be construed as epiphenomenal. For something to be
epiphenomenal – for it to fail to play a causal role – it has to exist in the
same explanatory space as that which it might have played a role in causing. But
as we’ve seen, the stubborn and strange fact is that consciousness, although
undeniably real (unlike ghosts or souls), doesn’t exist in the 3rd person explanatory space in
which its physical correlates exist. It can’t be found in the intersubjective
reality inhabited by its correlates, which is limited to public observables.
This means it can’t interact with its correlates – it can’t cause them, or be
caused by them – so isn’t in a position of being causally inert with respect to
them. When operating from a 3rd person, intersubjective perspective it’s a
category mistake to suppose consciousness is behaviorally epiphenomenal, where the
categories are two mutually non-interacting explanatory spaces. Consciousness
isn't epiphenomenal with respect to physical goings on, rather it's causally
orthogonal.

The worry
about consciousness being epiphenomenal is that it gets demoted to something
extraneous or second-class in comparison with the physical, a useless
accompaniment to what’s doing the real work in controlling action. But since
consciousness doesn’t exist in 3rd person explanatory space, none of
these things are true of it. We can relax about the fact that scientific
explanations won’t find a role for phenomenal feels like pain and pleasure in
explaining what we do, since that isn’t to dethrone consciousness, but only to
accept that 3rd person explanations are limited to observables. As
suggested above, however much science advances we’ll continue to conveniently
explain behavior by appealing to our phenomenal states, paying tribute to 1st
person subjective reality, to the fact that we are conscious creatures.
Consciousness will still be central to our lives – it cannot be dethroned since
it’s the inescapable, untranscendable condition of being subjects in the first
place.

Some might
worry that if consciousness doesn’t play a behavior-controlling role in the same
causal, explanatory space as the brain, we therefore lose power and control.
But, simply put, this worry fails to give enough credit to the marvels of
neurally instantiated cybernetics. The brain and body, in collaboration with
their environment, don’t need consciousness to get the behavioral job done, and
that, from a 3rd person perspective, is that.

Looking at
the world intersubjectively we can ask: where is
consciousness? It isn’t anywhere in the sense of being an observable phenomenon
directly available to science, but nevertheless it is empirically associated
with certain sorts of complex physical systems that do cognitive,
world-representing work. Human beings are one instance of such systems. The
philo-scientific project of doing full justice to the world in our descriptions
– what we think of as attaining maximum objectivity – can’t responsibly declare
consciousness non-existent, since after all here it is for each of us, an
ineluctable, non-illusory 1st person reality that each of us
sincerely attests to, a fantastically rich quality space within which we as
phenomenal subjects and our phenomenally presented worlds both exist. Moreover,
we have made great strides in pinning down the neural correlates of
consciousness (see note 10), so it’s to some extent an empirically tractable
phenomenon, albeit invisible to intersubjective observation. Why, therefore,
should we suppose that the private subjective reality of consciousness is
somehow suspect, or plays second fiddle to the public intersubjective reality of
what’s observationally available? An objective account of what’s real must
encompass both realities, along with the elements that play roles in their
respective explanatory spaces. How these realities arise and interrelate is the
puzzle facing those seeking a unified account of consciousness in nature.[12]

[3]
“The Myth of Double Transduction,” in the volume of the International
Consciousness Conference, Toward a Science of Consciousness II, The
Second Tucson Discussions and Debates, S. Hameroff, ed., A.W.
Kaszniak, and A.C. Scott, MIT Press, 1998, p. 97-107.

[4]
For work in progress along these lines, see
The appearance of reality. Where I differ with Metzinger and most
other representationalists is in denying that consciousness plays a
causal role in 3rd person accounts of behavior, the central
claim of the present paper.

[5] I take it that phenomenal experiences are
unequivocally real for the conscious subject, in that it seems difficult
to doubt the existence of the experience of pain, or any other
qualitative phenomenal feel I undergo. Physicalists doubt that
experiences are irreducibly mental phenomena, but for the most
part they don’t doubt that experiences are real, whatever they turn out
to be. If you doubt the reality of private phenomenal feels then the
question of mental causation, the major focus of this paper, doesn’t
arise for you.

[6]
Metzinger says “…the walls of the [ego] tunnel are impenetrable for us.
Even if we believe that something is just an internal construct, we can
experience it only as a given and never as constructed.
This fact may well be cognitively available to us (because we have a
correct theory or concept of it), but it is not attentionally or
introspectively available, simply because on the level of subjective
experience, we have no point of reference 'outside' the tunnel. Whatever
appears to us – however it is mediated – appears as reality.” The Ego
Tunnel, pp. 44-5, original emphasis.

[9] For a careful
assessment of current thinking on the (dim) prospects of finding a
causal role for phenomenal consciousness, see Jaegwon Kim’s
Physicalism, or Something Near Enough. In the closing section of
chapter one, “Mental Causation and Consciousness,” he says (original
emphasis): “…the problem of consciousness, or "the mystery of
consciousness," is solvable if consciousness is functionally
reducible--and I will argue that it is solvable only if
consciousness is functionally reducible. So the functional
irreducibility of consciousness entails the insolvability of both the
problem of consciousness and the problem of mental causation--at least
as the latter problem concerns consciousness. It is thus that the two
problems, that of mental causation and that of consciousness, turn out
to share an interlocking fate. What stands in the way of solving the
problem of mental causation is consciousness. And what stands in the way
of solving the problem of consciousness is the impossibility of
interpreting or defining it in terms of its causal relations to
physical/biological properties. They are indeed Weltknoten,
problems that have eluded our best philosophical efforts. They seem
deeply entrenched in the way we conceptualize the world and ourselves,
and seem to arise from some of the fundamental assumptions we hold about
each.”

[10]
For some recent research on the higher-level cognitive capacities and
neural processes that
correlate with consciousness, see
here.

[11]
Courtesy of
The Lippard Blog, here’s how married life might go without referring to one's qualitative
states, quoted from a New Yorker article by Larissa MacFarquhar
profiling neuroscientists Patricia and Paul Churchland:

One afternoon recently, Paul says, he was home making dinner when
Pat burst in the door, having come straight from a frustrating
faculty meeting. “She said, ‘Paul, don't speak to me, my serotonin
levels have hit bottom, my brain is awash in glucocorticoids, my
blood vessels are full of adrenaline, and if it weren't for my
endogenous opiates I'd have driven the car into a tree on the way
home. My dopamine levels need lifting. Pour me a Chardonnay, and
I'll be down in a minute.'

[12]
One line of inquiry suggests that reality as known – what’s taken to be real –
necessarily arises as a function of representation. Reality is
necessarily presented to knowers in terms of
representations, such that 1st and 3rd person
realities might arise as a function of two different sorts of
representational systems, one individual, instantiated by independent,
free-standing, mobile cognitive systems such as human persons, and one
collective, instantiated by an intersubjective conceptual system of
which science is an example. In
chapter one of Physicalism, or Something Near Enough, Jaegwon
Kim says “It may well be that our mind-body problem, or something close
to it, arises within any scheme that is rich enough to do justice to the
world as we experience it. It may well be that the problem is an
inexorable consequence of the tension between the objective world of
physical existence and the subjective world of experience, and that the
distinction between the objective and the subjective is unavoidable for
reflective cognizers and agents of the kind that we are.” Here Kim
recognizes the existence of the two worlds, the two realities,
that must somehow be conjoined in a unified philo-scientific account of
consciousness in nature. He suggests that they arise, perhaps, as a
function of our being cognizers, that is, being a certain sort of system
that represents the world. I develop this idea in
The appearance of reality, ms in progress.